Certain chemical solutions are sufficiently, chemically active to continually emit a gaseous by-product. Generally, the concern of the present application, are those solutions which generate gases at a very slow rate. Thus with time, the pressure in a closed vessel containing the solution will continue to increase unless relieved.
Such a problem has been addressed with the development of special, pressurized containers and closures. Typically, the containers are metalized, high strength receptacles, relatively expensive to manufacture. Alternately a special closure must be provided which relieves the pressure before opening; or extreme care must be taken.
An area employing chemical solutions giving rise to the problems noted above, is the photoresist utilized in the semiconductor and electronics industry. These are unique formulations which react, emitting a gas at a slow rate. The time for the gas pressure to build to a relatively dangerous level for the typical storage containers (32-128 fl. oz.) may be in the order of 6-12 months.
Further, therefore, there has been no simple, practical means for indicating the possible build up of pressure in the bottle.
Therefore, it is a primary object of this invention to provide an improved closure for bottles containing gas emitting solutions, which would provide both a warning of increase in gas pressure as well as partial relief from the developing pressure.
It is a further object to provide a relatively inexpensive and simple closure which will accomplish this.